Funt: High-tech harvest: 'Drone on the range'

It's possible that the weapons of choice to combat illegal immigration will turn out to be drones and robots.

We're not talking about patrolling the borders with Mexico -- although, in fact, drones are being tested there. The real breakthrough is in the fields, here in the Salinas Valley and elsewhere across the Salad Bowl of the West, where unmanned drones and robots are being deployed. The mission isn't to find undocumented farm workers; it's to replace them.

A decade from now the immigration problem that has proved so vexing for lawmakers and pundits will essentially solve itself through technology. Ironically, farmers and scientists aren't being inspired by political or social considerations; farming is changing out of necessity.

Currently there are as many as 2 million undocumented farmhands picking crops and planting fields in the U.S. But that's not enough to fill the need, and the pool of workers here illegally is plunging. According to a report by the Pew Hispanic Center, the number of people leaving Mexico to work in the U.S. has dropped by roughly 65 percent during the last decade.

Big agriculture has sought to counter this by lobbying in Washington for an easier path by which farm workers could gain citizenship. But they've also hedged the bet by investing in research that could turn the field jobs over to machines.

A firm in Mountain View, has developed a Lettuce Bot that thins plants in the field 20 to 40 times faster than a human can do it -- and the unit works day and night. Its inventor told the San Francisco Chronicle that the robot can thin a 15-acre field, normally a day's work for 25 people, in less than two hours.

Unmanned aerial vehicles are being tested in labs and fields across California, in anticipation of the 2015 deadline Congress has set for opening the skies to such vehicles for commercial use. But UAVs are already in wide use by farmers in Japan and Australia -- for spraying as well as surveillance to determine the spread of weeds and specific needs for water.

A manned spraying craft drops its chemicals from 10 or 15 feet above the ground, while a drone does the same work just inches away from the plants. Drones are also being tested for herding cattle and other livestock.

A San Diego research firm has invented a robot that prunes grapes. It also has a bot with eight arms and a built-in camera system that sweeps through groves picking oranges.

Modern Farmer magazine looked at all this and came up with the headline, "Drone, drone on the range."

It's all very exciting and may have the unintended consequence of moderating, if not eliminating, the nation's sharp divide over handling undocumented immigrants. In truth, farmers here as well as in Arizona and Florida have known for decades that undocumented workers are essential to their business, as well as to our food supply. For the most part, American citizens do not want the jobs.

Until now, there was no way around it. Farmhands arrived from south of the border, ag bosses winked, and Americans dined on fruits and vegetables at reasonable prices.

Technology is going to change that. Politicians may not deserve it, but robots and drones are going to allow them to solve the farming problem without getting their hands dirty.